Cutting insert and a milling tool

Abstract

A cutting insert for face milling and ramping includes an upper side defining an upper extension plane, a lower side defining a lower extension plane parallel with the upper extension plane, and an edge side extending around the cutting insert. A center axis extends perpendicularly through the upper and lower extension planes. An upper cutting edge forms four upper cutting edge portions having an identical length corresponding to a determined angle with respect to the center axis. A lower cutting edge forms four lower cutting edge portions ( 26 ), having an identical length corresponding to the determined angle with respect to the center axis. Each upper cutting edge portion is displaced angularly with respect to the center axis in relation to one of the lower cutting edge portions with a displacement angle being greater than zero and less than the determined angle.

The invention claimed is: 
     
       1. A cutting insert configured for chip-removing machining and for being mounted in a cutter body for face milling and ramping of a workpiece, comprising:
 an upper side defining an upper extension plane; 
 a lower side defining a lower extension plane being parallel with the upper extension plane, wherein a center axis extends perpendicularly through the upper extension plane and the lower extension plane; 
 an upper cutting edge extending around the upper side and forming at least two upper cutting edge portions, each having a length corresponding to a determined angle with respect to the center axis; 
 a lower cutting edge extending around the lower side and forming at least two lower cutting edge portions, each having a length corresponding to said determined angle with respect to the center axis; and 
 an edge side extending around the cutting insert, the edge side including a transition portion extending around the cutting insert and dividing the edge side into an upper side portion associated with the upper cutting edge and a lower side portion associated with the lower cutting edge, the upper side portion forming an acute angle with the upper extension plane, and the lower side portion forming an acute angle with the lower extension plane, wherein the cutting insert is indexable, to different index positions, for permitting cutting with at least one of the at least two upper cutting edge portions with the upper side forming a chip surface, or at least one of the at least two lower cutting edge portions with the lower side forming a chip surface, and wherein the length of each of the at least two upper cutting edge portions is equal to the length of each of the lower cutting edge portions, wherein each of the at least two upper cutting edge portions is displaced angularly with respect to the center axis in relation to one of the at least two lower cutting edge portions with a displacement angle being greater than zero and less than said determined angle, the upper cutting edge being configured such that one of the at least two upper cutting edge portions forms a main cutting edge and an adjacent upper cutting edge portion forms a minor cutting edge in one of said index positions, and wherein the lower cutting edge is configured in such that one of the at least two lower cutting edge portions forms a main cutting edge and an adjacent lower cutting edge portion forms a minor cutting edge in another one of said index positions. 
 
     
     
       2. A cutting insert according to  claim 1 , wherein the upper side portion comprises at least two upper side surfaces associated with a respective one of the at least two upper cutting edge portions, and wherein the lower side portion comprises at least two lower side surfaces associated with a respective one of the at least two lower cutting edge portions. 
     
     
       3. A cutting insert according to  claim 2 , wherein each of the at least two upper and lower side surfaces is configured to form a clearance surface in one of said index positions and configured to form a support surface in another of said index positions and thus to abut a support surface of said cutter body when being mounted in the cutter body. 
     
     
       4. A cutting insert according to  claim 1 , wherein the transition portion has a wave-like shape seen in a direction parallel to the upper and lower extension planes. 
     
     
       5. A cutting insert according to  claim 1 , wherein the transition portion comprises a groove extending around the cutting insert. 
     
     
       6. A cutting insert according to  claim 1 , wherein the displacement angle is greater than zero and less than 50% of said determined angle. 
     
     
       7. A cutting insert according to  claim 1 , wherein the at least two upper cutting edge portions and the at least two lower cutting edge portions are identical. 
     
     
       8. A cutting insert according to  claim 1 , wherein the upper cutting edge comprises three upper cutting edge portions and the lower cutting edge comprises three lower cutting edge portions. 
     
     
       9. A cutting insert according to  claim 1 , wherein the upper cutting edge comprises four upper cutting edge portions and the lower cutting edge comprises three lower cutting edge portions. 
     
     
       10. A cutting insert according to  claim 1 , wherein the upper cutting edge comprises five upper cutting edge portions and the lower cutting edge comprises three lower cutting edge portions. 
     
     
       11. A cutting insert according to  claim 1 , wherein the cutting insert is single-handed. 
     
     
       12. A milling tool comprising a cutter body and a plurality of cutting inserts, wherein the cutting inserts are mounted in the cutter body and configured to permit alternating face milling and ramping of a workpiece, each of said cutting inserts comprising:
 an upper side defining an upper extension plane; 
 a lower side defining a lower extension plane parallel with the upper extension plane, wherein a center axis extends perpendicularly through the upper extension plane and the lower extension plane; 
 an upper cutting edge extending around the upper side and forming at least two upper cutting edge portions, each having a length corresponding to a determined angle with respect to the center axis; 
 a lower cutting edge extending around the lower side and forming at least two lower cutting edge portions, each having a length corresponding to said determined angle with respect to the center axis; and 
 an edge side extending around the cutting insert, the edge side including a transition portion extending around the cutting insert and dividing the edge side into an upper side portion associated with the upper cutting edge and a lower side portion associated with the lower cutting edge, the upper side portion forming an acute angle with the upper extension plane, and the lower side portion forming an acute angle with the lower extension plane, wherein the cutting insert is indexable, to different index positions, for permitting cutting with at least one of the at least two upper cutting edge portions with the upper side forming a chip surface, or at least one of the at least two lower cutting edge portions with the lower side forming a chip surface, and wherein the length of each of the at least two upper cutting edge portions is equal to the length of each of the lower cutting edge portions, wherein each of the at least two upper cutting edge portions is displaced angularly with respect to the center axis in relation to one of the at least two lower cutting edge portions with a displacement angle being greater than zero and less than said determined angle.